In vitro neuraminidase inhibitory concentration (IC50) of four neuraminidase inhibitors against clinical isolates of the influenza viruses circulating in the 2010–2011 to 2014–2015 Japanese influenza seasons

Effectiveness of intravenous peramivir for the treatment of influenza A/H3N2 and influenza B/Victoria in hospitalized children

OBJECTIVE

To optimize the medication administered to children with influenza, we evaluated the effectiveness of peramivir in hospitalized children with influenza A/H3N2 and influenza B/Victoria.

METHODS

A retrospective study was conducted from October 2019 to March 2020 in children aged 29 days to 18 years with influenza A/H3N2 or B/Victoria. A total of 97 patients were enrolled and treated with intravenous infusion of peramivir.

RESULTS

The duration of influenza virus nucleic acid positivity in the influenza A/H3N2 group (3 days) was shorter than that in the influenza B/Victoria group (4 days) (P = 0.008). The remission time of fever symptoms in the influenza A/H3N2 group was 14 h, which was significantly shorter than that in the influenza B/Victoria group (26 h) (P = 0.042). In the 6-18 years age group, the median duration of virus nucleic acid positivity for children with influenza B/Victoria (4 days) was longer than that for children with influenza A/H3N2 (2 days) (P = 0.005). The incidence of adverse drug reactions (ADRs) with peramivir in the influenza A/H3N2 group and the influenza B/Victoria group was 2.04% (n = 1/49) and 4.17% (n = 2/48), respectively (P = 0.617).

CONCLUSIONS

A difference in the effectiveness of peramivir against different subtypes of influenza was observed. Compared to those infected with influenza B/Victoria, the children infected with influenza A/H3N2 experienced a significantly shorter duration of influenza virus nucleic acid positivity and remission time of fever symptoms.

Impact of early neuraminidase inhibitor treatment on clinical outcomes in patients with influenza B-related pneumonia: a multicenter cohort study

The aim of this study is to evaluate the impact of early (within 2 days after disease onset) neuraminidase inhibitor (NAI) administration on clinical outcomes in patients with laboratory-confirmed influenza B-related pneumonia (FluB-p). This was a multicenter study conducted from 1 January 2013 to 1 May 2019. Data of immunocompetent adult and adolescent FluB-p patients hospitalized at five different teaching hospitals in China were retrospectively collected, including demographic and clinical features as well as clinical and treatment outcomes. Univariate and multivariate logistic regression analyses were performed to assess the effects of early NAI administration on clinical outcomes in FluB-p patients. In total, 386 hospitalized patients with community-onset FluB-p were included in this study, of whom 39.6% (153/386) were treated with NAI early. After adjusting for the weighted propensity scores of treatment, systemic corticosteroid, and antibiotic uses, the results of multivariate logistic regression model indicated that early NAI treatment was associated with the decreased risks of invasive ventilation [odd ratio (OR) 0.325, 95% confidence interval (CI) 0.123-0.858; p = 0.023), admittance to intensive care unit (OR 0.425, 95% CI 0.204-0.882; p = 0.022), and 30-day mortality (OR 0.416, 95% CI 0.184-0.944, p = 0.036)] in FluB-p patients. In addition, the multivariate logistic regression analysis revealed that early NAI treatment (OR 0.306, 95% CI 0.063-0.618; p = 0.010) was an independent predictor for 30-day mortality in patients with FluB-p. Early NAI treatment was associated with better clinical outcomes in FluB-p patients, which supports the recommendations of its use in severe influenza illness.

Consecutive influenza surveillance of neuraminidase mutations and neuraminidase inhibitor resistance in Japan

Background

The large consumption of neuraminidase inhibitors (NAIs) for the treatment of influenza virus infections places Japan at risk of becoming the epicenter of the global spread of NAI‐resistant viruses.

Objective

To clarify NA amino acid mutations of epidemic influenza viruses in Japan and their related NAI resistance.

Methods

A total of 1791 samples, including 396 A/H1N1pdm09, 1117 A/H3N2, and 278 B isolates, were collected to determine of their 50% inhibitory concentration (IC₅₀) values by NAIs (oseltamivir, zanamivir, peramivir, and laninamivir) during the Japanese seasons from 2011‐2012 to 2016‐2017. Then, 380 samples including 49 A/H1N1pdm09, 251 A/H3N2, and 80 B isolates were sequenced for the entire NA genes.

Results

Neuraminidase inhibitor‐resistant A/H1N1pdm09 viruses were detected at a frequency of 1.3% (5/396 isolates) in the epidemic seasons. None of the A/H3N2 and B viruses developed resistance to any of the four NAIs during the six seasons. Only five and 13 AA mutations were detected in the NA catalytic sites of A/H1N1pdm09 and A/H3N2 viruses, respectively. No mutations were observed in the catalytic sites of B viruses. Four of the five mutations in the catalytic sites of A/H1N1pdm09 consisted of H275Y, which was related to high resistance to oseltamivir and peramivir. Most (10/13) of the catalytic site mutations in A/H3N2 were associated with MDCK‐passaged induction (D151G/N). Finally, no mutations related to substantial NAI resistance were detected in the A/H3N2 and B viruses examined.

Conclusion

These findings suggest that the NA catalytic sites of influenza viruses are well preserved. Even in Japan, no spread of NAI‐resistant viruses has been observed, and A/H1N1pdm09 viruses carrying H275Y remain limited.

Clinical effectiveness of four neuraminidase inhibitors (oseltamivir, zanamivir, laninamivir, and peramivir) for children with influenza A and B in the 2014-2015 to 2016-2017 influenza seasons in Japan

The clinical effectiveness of four neuraminidase inhibitors (NAIs) (oseltamivir, zanamivir, laninamivir, and peramivir) for children aged 0 months to 18 years with influenza A and B were investigated in the 2014-2015 to 2016-2017 influenza seasons in Japan. A total of 1207 patients (747 with influenza A and 460 with influenza B) were enrolled. The Cox proportional-hazards model using all of the patients showed that the duration of fever after administration of the first dose of the NAI was shorter in older patients (hazard ratio = 1.06 per 1 year of age, p < 0.001) and that the duration of fever after administration of the first dose of the NAI was shorter in patients with influenza A infection than in patients with influenza B infection (hazard ratio = 2.21, p < 0.001). A logistic regression model showed that the number of biphasic fever episodes was 2.99-times greater for influenza B-infected patients than for influenza A-infected patients (p < 0.001). The number of biphasic fever episodes in influenza A- or B-infected patients aged 0-4 years was 2.89-times greater than that in patients aged 10-18 years (p = 0.010), and the number of episodes in influenza A- or B-infected patients aged 5-9 years was 2.13-times greater than that in patients aged 10-18 years (p = 0.012).

Duration of fever and other symptoms after the inhalation of laninamivir octanoate hydrate in the 2016/17 Japanese influenza season; comparison with the 2011/12 to 2015/16 seasons

The duration of fever and symptoms after laninamivir octanoate hydrate (laninamivir) inhalation were investigated in the Japanese 2016/17 influenza season and the results were compared with those of the 2011/12 to 2015/16 seasons. A total of 1278 patients were evaluated for the duration of fever and symptoms in the six studied seasons. In the 2016/17 season, the influenza types/subtypes of the patients were 6 A (H1N1)pdm09 (2.9%), 183 A (H3N2) (87.6%), and 20 B (9.6%). The respective median durations of fever for A (H1N1)pdm09, A (H3N2), and B were 38.0, 33.0, and 38.5 h, without significant difference (p = 0.9201), and the median durations of symptoms were 86.5, 73.0, and 99.0 h, with significant difference (p = 0.0342). The median durations of fever and symptoms after laninamivir inhalation were quite consistent for the six studied seasons for A (H1N1)pdm09, A (H3N2), and B, without any significant differences. The percentage of patients with unresolved fever patients displayed a similar pattern through the six studied seasons for all these virus types. There was no significant difference in the duration of fever or symptoms between the Victoria and Yamagata lineages in the 2016/17 season and those of the previous studied seasons. Over the seasons tested, ten adverse drug reactions (ADRs) were reported from 1341 patients. The most frequent ADR was diarrhea and all ADRs were self-resolving and not serious. These results indicate the continuing clinical effectiveness of laninamivir against influenza A (H1N1)pdm09, A (H3N2), and B, with no safety issues.

In vitro neuraminidase inhibitory concentration (IC50) of four neuraminidase inhibitors in the Japanese 2016-17 season: Comparison with the 2010-11 to 2015-16 seasons

To assess the extent of susceptibility to the four most commonly used neuraminidase inhibitors (NAIs) in the viruses epidemic in the 2016-17 Japanese influenza season, we measured the 50% inhibitory concentration (IC₅₀) of these NAIs for influenza virus isolates from patients and compared them with the results from the 2010-11 to 2015-16 seasons. Viral isolation was done with specimens obtained prior to treatment, and the type and subtype was determined by RT-PCR using type- and subtype-specific primers. The IC₅₀ was determined by a neuraminidase inhibition assay using a fluorescent substrate. A total of 276 virus isolates, 6 A (H1N1)pdm09 (2.2%), 249 A (H3N2) (90.2%), and 21 B (7.6%), had the IC₅₀ measured for the four NAIs. B isolates included 11 (52.4%), 9 (42.9%), and one (4.8%) of the Victoria, Yamagata, and undetermined strains, respectively. No A (H1N1)pdm09 with highly reduced sensitivity for oseltamivir was found in the 2016-17 season. No isolate with highly reduced sensitivity to the four NAIs have been found for A (H3N2) or B from the 2010-11 to 2016-17 seasons. No significant trend of increase or decrease was found in the geometric mean IC₅₀s of the four NAIs during the seven studied seasons. These results indicate that the sensitivity to the four commonly used NAIs has been maintained and that any change in the effectiveness of these NAIs would be minute. Common usage of NAIs for patient treatment has not been a driving force in the selection of NAI resistant viruses.